Auxiliary hydraulic control system

ABSTRACT

An auxiliary hydraulic system for a working vehicle having an operator station is disclosed herein. The system includes a hydraulic pump for providing hydraulic fluid under pressure, auxiliary hydraulic fittings for connection to auxiliary attachments, and electrically-actuated auxiliary valve assemblies for controlling the supply of hydraulic fluid from the pump to the fittings in response to control signals. The system also includes an operator control console mounted at the operator station and including control levers moveable between different flow positions, flow limit input devices for setting flow limits for the control levers, and a console control circuit for generating command signals based upon the positions of the control levers and the flow limits. The command signals are transmitted to an auxiliary control circuit which generates the control signals in response thereto and applies the control signals to the auxiliary valve assemblies. Thus, the supply of fluid to the auxiliary valve fittings depends upon the positions of the control levers and the flow limits which are controlled by an operator from an integrated operator control console.

FIELD OF THE INVENTION

The present invention relates generally to auxiliary hydraulic systemsfor working vehicles. In particular, the present invention relates to acontrol system for an auxiliary hydraulic system, the control systemincluding an operator control console including control levers andmaximum flow control devices.

BACKGROUND OF THE INVENTION

Working vehicles often include auxiliary hydraulic systems configured tosupply pressurized hydraulic fluid from a vehicle hydraulic pump toauxiliary equipment or attachments. For example, agricultural andconstruction equipment vehicles (e.g., tractors; tractor-loaders;skid-steer loaders) may be coupled to attachments such as augers,grapples, sweepers, landscape rakes, backhoes, scarfers, snowblowers,stabilizers, raising and lowering implements or other attachments drivenby hydraulic actuators such as hydraulic cylinders or hydraulic motors.

The attachments can be referred to as "auxiliary" equipment since theyare typically connected to a vehicle to perform a particular job, andthen disconnected when the job is complete. Accordingly, the workingvehicles include external fluid fittings to facilitate connecting anddisconnecting the hydraulic fluid supply lines of the attachments to thevehicles' auxiliary hydraulic systems. The auxiliary hydraulic systemsinclude valves configured to control the supply of hydraulic fluidflowing through the fittings. The use of auxiliary equipment increasesversatility of working vehicles by allowing the vehicles to performdifferent functions at different times.

Different attachments impose varying requirements on auxiliary hydraulicsystems with respect to timing, rate and control of fluid flow. Forexample, an attachment equipped with a hydraulic motor (e.g., auger) mayrequire a continuous flow of fluid while an attachment equipped with ahydraulic cylinder actuator (e.g., plow) may only require a flow offluid for a discrete period. A desired rate of flow may depend upon theweight of an implement or on the work being performed by an attachment.For example, the flow rate required to raise an implement at a desiredspeed (e.g., fast enough for efficiency yet slow enough for safety) maybe higher for a relatively heavy implement than for a relatively lightimplement. Closed-loop control based upon feedback signals may or maynot be required. For example, a plow can be raised and lowered betweendesired raise and lower positions by a hydraulic cylinder actuator basedon position feedback signals while a landscape rake may be raised orlowered by applying a fluid flow for a period sufficient to fully raiseor lower the rake. Further, an auxiliary hydraulic system may berequired to supply fluid to an attachment at a maximum flow rate in somesituations and at a "feathered" flow rate (e.g., proportional control)in other situations such as during precision operations.

An auxiliary hydraulic system may also be required to provide hydraulicfluid flows to a number of auxiliary attachments having different fluidflow timing, rate and control requirements. For example, a tractor couldbe required to provide hydraulic fluid to simultaneously raise and lowera plow based upon position feedback signals, raise and lower a rake, anddrive an auger.

Accordingly, it would be advantageous to provide an improved auxiliaryhydraulic system capable of providing pressurized fluid to attachmentsin continuous or timed modes, of providing fluid to attachments at flowrates which can be set by an operator, of providing fluid to certainattachments using closed-loop control based upon feedback signals, andof providing fluid to attachments at maximum or feathered flow rates.Further, it would be advantageous to provide an improved auxiliaryhydraulic system for supplying pressurized fluid to attachments havingvarying timing, rate and control requirements.

It would also be advantageous to provide an improved operator controlconsole for a working vehicle equipped with an auxiliary hydraulicsystem. Advantages which can be realized by the improved operatorcontrol console disclosed herein include the versatility to providefluid flow command signals for attachments with varying timing, rate andcontrol requirements. The command signals can be used to controldifferent types of attachments which may be coupled to auxiliaryhydraulic systems. Further, the operator control console provides flowlimit input devices to allow an operator to set maximum flow rates foreach auxiliary valve within the system. The operator control consoleincludes an interface for communication across a vehicle databus.

SUMMARY OF THE INVENTION

One embodiment of the invention provides an operator control console fora working vehicle equipped with an auxiliary hydraulic system includinga fluid pump, a plurality of fittings, an auxiliary valve assembly forcontrolling the flow of fluid between the fluid pump and the fittings inresponse to control signals, and an auxiliary control circuit forreceiving command signals and generating the control signals therefrom.The operator control console includes a console cover, and at least onecontrol lever extending above the console cover and moveable between aplurality of positions including neutral and maximum flow positions. Theoperator control console further includes a sensing circuit forgenerating a signal representative of the position of the control lever,at least one flow limit input device including a handle extending abovethe console cover and configured to generate a signal representative ofa flow limit, and a console control circuit coupled to the sensingcircuit and the flow limit input device. The console control circuit isconfigured to generate the command signals to correspond to a flow ratebetween a neutral flow rate and the flow limit depending upon theposition of the control lever.

Another embodiment of the invention provides an auxiliary hydraulicsystem for a working vehicle having an operator station. The auxiliaryhydraulic system includes a hydraulic pump supported by the vehicle forproviding hydraulic fluid under pressure, a plurality of auxiliaryhydraulic fittings configured to be connected to auxiliary attachments,a plurality of electrically-actuated auxiliary valve assembliesconfigured to control the supply of hydraulic fluid from the pump to theauxiliary hydraulic fittings in response to control signals, and anoperator control console mounted at the operator station. The controlconsole includes a console cover, and a plurality of control leversextending above the console cover and moveable between a plurality ofpositions including neutral and maximum flow positions. The controlconsole further includes a plurality of sensing circuits, each sensingcircuit coupled to one of the control levers for generating a signalrepresentative of the position of the respective control lever, aplurality of flow limit input devices, each flow limit input deviceincluding a handle extending above the console cover and configured togenerate a signal representative of a flow limit for one of the valveassemblies, and a console control circuit coupled to the sensingcircuits and the flow limit input devices. The console control circuitis configured to generate command signals for each valve assembly whichcorrespond to a flow rate between a neutral flow rate and the flow limitfor the respective valve assembly depending upon the position of therespective control lever. The auxiliary hydraulic system furtherincludes an auxiliary control circuit coupled to the auxiliary valveassemblies and the operator control console. The auxiliary controlcircuit is configured to receive the command signals and to generate thecontrol signals therefrom, and to apply the control signals to the valveassemblies, whereby the supply of hydraulic fluid to the auxiliary valvefittings depends upon the positions of the control levers and the flowlimits.

Another embodiment of the invention provides an operator control consolefor a working vehicle equipped with a communication bus. The operatorcontrol console includes a console cover, a first input device extendingabove the console cover and moveable between a plurality of positionsincluding a first predefined position, and a sensing circuit coupled tothe first input device and configured to generate a signalrepresentative of the position of the first input device. The controlconsole further includes a second input device extending above theconsole cover and configured to generate a signal representative of aparameter limit, and a control circuit coupled to the sensing circuitand the second input device. The control circuit is configured togenerate command signals which correspond to the parameter limit whenthe first input device is moved to the first predefined position. Thecontrol console further includes an interface circuit coupled to thecontrol circuit for formatting the command signals for transmission onthe communication bus.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more fully understood from the followingdetailed description, taken in conjunction with the accompanyingdrawings, wherein like reference numerals refer to like parts, in which:

FIG. 1 is a block diagram representing a working vehicle equipped withan auxiliary hydraulic system for supplying pressurized hydraulic fluidto attachments, the auxiliary hydraulic system including an armrestcontrol unit, an auxiliary control unit and auxiliary valves;

FIG. 2 is a perspective view of the armrest control unit of FIG. 1 whichshows command devices for the auxiliary hydraulic system including valvecontrol lever assemblies with kick-out timer disable switches, a valvecontrol switch, flow limit control knobs, a kick-out timer set knob, andan extend/retract limit switch;

FIGS. 3A-3G are views of each valve control lever assembly of FIG. 2including (A) a front perspective view, (B) a rear perspective view, (C)a front plan view, (D) a right-side plan view, (E) a bottom plan view,(F) a top plan view, and (G) a sectional view taken along line 3G--3G inFIG. 3D;

FIG. 4 is a block diagram of the armrest control unit of FIG. 1 whichshows the command devices and an armrest control circuit;

FIG. 5 is a process diagram for the processing circuit of the armrestcontrol unit shown in FIG. 4;

FIG. 6 shows scaling performed by the processing circuit of the armrestcontrol unit to generate command signals from the auxiliary valvecontrol lever positions;

FIG. 7 shows scaling performed by the processing circuit of the armrestcontrol unit to generate command signals from the auxiliary flow limitcontrol knobs and the automatic kick-out timer set knob;

FIG. 8 is a block diagram of the auxiliary control unit shown in FIG. 1;

FIGS. 9A-9C are process diagrams for the processing circuit of theauxiliary control unit;

FIG. 10 is a state event table showing how the state values for theauxiliary valves are updated;

FIG. 11 is a memory map showing the calibration and configuration valuesin non-volatile memory within the armrest control unit shown in FIG. 1;

FIG. 12 is a block diagram of an instrumentation control unit (ICU) usedfor providing an operator input and output interface during calibrationand configuration of the auxiliary hydraulic system and other systems;and

FIG. 13 is a block diagram showing the calibration procedure for theauxiliary hydraulic and other systems.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a working vehicle 10 is equipped with an auxiliaryhydraulic system 12 for supplying pressurized hydraulic fluid toattachments 14-22. Working vehicle 10 can be an agricultural orconstruction equipment vehicle and attachments 14-22 include hydraulicactuators having independent hydraulic fluid flow timing, rate andcontrol requirements.

Auxiliary hydraulic system 12 includes an armrest control unit 24, anauxiliary control unit 26 and auxiliary valve assemblies 28-36. Armrestcontrol unit 24 is mounted at an operator station of the vehicle (e.g.,cab) and includes various input or command devices 38 configured togenerate electrical command signals. Command devices 38 include valvecontrol levers 40-46 for controlling the flow of fluid through auxiliaryvalve assemblies 28-34, respectively, a valve control switch 48 forcontrolling the flow through auxiliary valve assembly 36, automatickick-out timer disable switches 50-56 for disabling an automatickick-out function for valve assemblies 28-34, flow limit control knobs58-66 for setting flow limits for valve assemblies 28-36, a kick-outtimer set knob 68 for setting an automatic kick-out time period forvalve assemblies 28-36, and an extend and retract limit switch 70 forsetting extend/retract limits for attachment 14.

Potentiometers associated with valve control levers 40-46, flow limitcontrol knobs 58-66, and kick-out timer set knob 68 generate electricalsignals representing the position of the respective lever or knob. Valvecontrol switch 48 is a three-position switch with extend, neutral andretract positions. Kick-out timer disable switches 50-56 aretwo-position switches with non-continuous (or timed) and continuous (ormotor) positions. Extend and retract limit switch 70 is a three-positionswitch with extend limit, neutral and retract limit positions.

Armrest control unit 24 generates command signals which reflect thesettings of command devices 38, and transmits the command signals via avehicle data bus 72 to other vehicle systems. Preferably, bus 72conforms to the standards of SAE J-1939 ("Recommended Practice for aSerial Control and Communications Vehicle Network").

Auxiliary control unit 26 receives the command signals from bus 72,generates valve control signals on conductors 74-82 from the commandsignals, and applies the control signals via conductors 74-82 to valveassemblies 28-36. Valve assemblies 28-36 also receive a flow ofpressurized hydraulic fluid from a source 84 (e.g., a pump) via fluidhoses or conduits 86, and supply a flow of pressurized fluid to eachauxiliary hydraulic fitting 88-96 via hoses 98-106 in response to thecontrol signals on conductors 74-82. Auxiliary hydraulic fittings 88-96are configured for easy connection and disconnection to attachments14-22. The fluid supply network between auxiliary hydraulic system 12and attachments 14-22 can have other configurations such as usingmultiple hoses for each attachment.

In one embodiment, each auxiliary valve assembly 28-36 includes astepper motor, a valve interface or backcap operated by the steppermotor and a valve fluidly coupled between source 84 and the respectivefitting 88-96.

The stepper motors receive power and control signals 74-82 fromauxiliary control unit 26. Each stepper motor includes a rotor driven bytwo direct current (DC) phases or coils controlled by four controllines. The rotor is rotated in steps (e.g., 1/4 revolution/step) ineither direction in response to changes in the polarity of the coils.The number of steps needed for the valve to reach a desired valveposition is controlled by a stepper motor controller (FIG. 8) inresponse to the command signals from armrest control unit 24.

The valve interface in each valve assembly 28-36 includes a worm geardriven by the rotor and coupled to the valve. Rotation of the rotorcauses the worm gear to push or pull on the valve, thereby opening orclosing the valve and changing the flow of fluid through the valve. Thevalve is moved into a desired position by tracking the number of steps.For example, the valve is moved into float position after apredetermined number of steps (e.g., 270 steps or 270 quarter rotationsof the worm drive). Such stepper motors are available from AppliedMotion, and systems for controlling the positioning of valves usingstepper motors are available from Commercial Intertech. Alternatively,valve positions could be controlled using sensed valve position feedbacksignals.

Auxiliary control unit 26 receives electrical power from the vehiclebattery through an ignition key switch 108 and a fuse 110. Auxiliarycontrol unit 26 may also receive a feedback signal via line 112 from anoptional sensor 114 coupled to attachment 14. Sensor 114 may be, forexample, a cylinder position sensor (e.g., LVDT or potentiometer)configured to sense the position of a hydraulic cylinder in attachment14. Feedback signal 112 can be used by auxiliary control unit 26 as acontrol input in a cylinder position mode of operation wherein the fluidflow is controlled to move a cylinder between extend and retractpositions set by limit switch 70.

Referring to FIG. 2, command devices 38 are mounted to a console cover120 of armrest control unit 24 for convenient operator access (kick-outtimer disable switches 50-56 are internal to armrest control unit 24and, thus, are not visible in FIG. 2). Alternatively, an operatorcontrol console configured differently from armrest control unit 24 canbe used. Console cover 120 has two surface portions 122 and 124. Amoveable cover 126 rotates about a hinge 128 to cover surface portion124 and the command devices 38 mounted on second surface portion 124(e.g., flow limit control knobs 58-64; limit switch 70). Cover 126prevents accidental movement of the covered command devices, simplifiesthe interface presented to the operator during normal operation, andprovides an armrest for the operator's comfort.

Armrest control unit 24 may also include command devices for controllingother functions of vehicle 10. For example, armrest control unit 24 mayinclude a throttle control 130 with a bump switch 132, a hitch up/downswitch 134, a hitch draft force potentiometer 136, a hitch positioncontrol 138, a creeper switch 140, a mechanical front-wheel drive (MFD)switch 142, a differential lock (DL) switch 144, a power take-off (PTO)switch 146, and hitch travel, drop speed and upper limit potentiometers148-152. Signals from these command devices may also be transmitted byarmrest control unit 24 via vehicle data bus 72. Armrest control unit 24may be adjustably positioned relative to the operator's seat by assembly154 for the convenience of the operator.

The high degree of integration of command devices 38 in armrest controlunit 24 provides a convenient and inexpensive operator interface to thevarious control systems of vehicle 10. For example, an operator canfully control auxiliary hydraulic system 12 from a single console, andthe expense and inconvenience associated with additional control panelsare avoided.

Referring to FIGS. 3A-3G, each valve control lever 40-46 is a part of acontrol lever assembly 160 mounted beneath console cover 120 by a frameor bracket 162. Bracket 162 includes extended members having bolt holes164 to facilitate attachment to console cover 120 such that controllevers 40-46 extend above the cover through an elongated passage.Alternatively, bracket 162 can be mounted to an internal frame beneathconsole cover 120.

A first end of control lever 40 is rotatably mounted to bracket 162 by apivot 166. Thus, linear movement of control lever 40 within theelongated passage defined by console cover 120 causes a second end ofcontrol lever 40 to move along arc 168. The second end of control lever40 extends above console cover 120 and is connected to a handle or knob170.

Control lever 40 moves along a detent plate or track 172 attached tobracket 162. Lever detent recesses 174-178 are defined within track 172,and are connected by a recessed sliding pathway or groove 180. Track 172is preferably made of plastic, and track 172 includes raised portions orbumps 182 adjacent to recesses 174-178 for increasing the force requiredto move control lever 40 into and out of recesses 174-178. Extend orraise detent recess 174 is at the front of track 172, retract or lowerdetent recess 176 is near the rear of track 172 and float detent recess178 is beyond retract detent recess 176. Bumps 182 give a tactile feelthat a detent position is imminent.

A protrusion 184 associated with control lever 40 is guided by track 172to move within extend detent recess 174 when control lever 40 is movedto an extend or raise detent position, retract detent recess 176 whencontrol lever 40 is moved to a retract or lower detent position, andfloat detent recess 178 when control lever 40 is moved to a floatposition. Protrusion 184 is otherwise guided along groove 180 whencontrol lever 40 is in a proportional extend, neutral or proportionalretract position. Preferably, protrusion 184 is a metal or plastic balllocated within an aperture of control lever 40 and biased against track172 by a detent spring 186.

Control lever 40 is biased into a neutral position between recesses 174and 176 by a centering spring 188 coupled to bracket 162. Preferably,spring 188 connects between supports 190 and 192 extending from plates194 and 196, respectively. Plates 194 and 196 are adjacent to each otherbetween control lever 40 and bracket 162, and are rotatable about pivot166 as control lever 40 pushes against the respective support. Plates194 and 196 include stop members 198 and 200, respectively, whichcontact a stop 202 extending from bracket 162 to prevent supports 190and 192 from rotating in the clockwise and counter-clockwise directions,respectively, in FIG. 3D. Control lever 40 includes a pair of stoppingmembers 204 and 206 which contact stop 202 to prevent the rotation ofthe control lever past the extend detent and float detent positions.Alternatively, track 172 could include a neutral detent recess betweenrecesses 174 and 176 for receiving protrusion 184 to define a neutralposition.

Control lever assembly 160 also includes a control lever guide or leverlock assembly 208 rotatably mounted to bracket 162. The axis of rotation210 (FIG. 3F) is parallel to the direction of linear movement of controllever 40. Guide 208 has a cylindrical, elongated center portion betweentwo ends, and is made of injection-molded nylon. An opening 212 throughthe center portion has adjacent longitudinal slots 214-222 of differentlengths along the direction of linear movement of lever 40. The frontend of guide 208 includes an arm 224 projecting above console cover 120(see FIG. 2). An operator can rotate guide 208 about axis 210 byapplying a force to arm 224. Arm 224 can include an extending member ora thumbwheel.

A clutch plate 226 extends downwardly from the front end of guide 208 inparallel with a clutch plate 228 of bracket 162. Clutch plate 226 hasfive recesses 230 engageable with a protrusion 232 extending from clutchplate 228. Protrusion 232 is preferably a coined semisphere stamped intosteel bracket 162. The detent mechanism formed by clutch plates 226 and228 releasably retains guide 208 in one of five rotational positions asguide 208 rotates about axis 210, each rotational position correspondingto one longitudinal slot of opening 212. Since control lever 40 ismoveable within the one slot, the range of linear movement of controllever 40 depends upon the rotational position of guide 208. Other typesof detent mechanisms could also be used.

When arm 224 is in the LOCKED rotational position ("C" in FIG. 2),control lever 40 is retained against movement by slot 214 in the neutralposition. When arm 224 is in FLOAT LOCKOUT position ("F"), slot 216allows movement between the neutral, extend detent and retract detentpositions but not into the float detent position. When arm 224 is inFULL TRAVEL position ("1"), slot 218 allows movement over the full rangeof travel along track 172. When arm 224 is in LOADER position ("L"),slot 220 allows movement over the full range of travel except for theextend detent position. Finally, when arm 224 is in MOTOR position("M"), slot 222 allows movement only between the retract detent andfloat detent positions.

Control lever assembly 160 also includes kick-out timer disable switch50 mounted to bracket 162. Switch 50 is a two-position micro-switchcontrolled by a lever 234 which is actuated by a cam 236 at the rear endof guide 208 (FIG. 3B). Cam 236 can be a lower edge of guide 208, or amember extending from guide 208, such that actuation of switch 50depends upon the rotational position of guide 208. Switch 50 is normallyopen and is closed only in the MOTOR rotational position of guide 208,and is used to select between timed and continuous fluid flow.Micro-switch 50 can be obtained, for example, from Burgess Inc.

Control lever assembly 160 also includes a sensing circuit 238 mountedto bracket 162 and coupled to control lever 40 for generating signalsrepresenting the control lever position. Sensing circuit 238 preferablyincludes a potentiometer (e.g., 4K ohm pot) coupled to pivot 166 anddirectly actuated by control lever 40. Sensing circuit 238 could alsoinclude a digital encoder which generates pulse or digital outputsignals, a variable capacitance sensing circuit, or an array ofelectrical detectors for sensing the control lever position.

Conductors 240 connect potentiometer 238 and switch 50 to an armrestcontrol circuit (not shown in FIG. 3) via connector 242. The armrestcontrol circuit provides excitation signals for reading potentiometer238 (e.g., regulated +8V) and switch 50 (e.g., +12V switch power).However, control lever assembly 160 can be connected via connector 242to other types of control systems.

Referring to FIG. 4, armrest control unit 24 includes a console controlcircuit 260 which receives signals from command devices 38, processesthe signals, and transmits command signals onto data bus 72. Controlcircuit 260 includes signal conditioning and multiplexing circuits 262and 264 for receiving the analog and digital command signals,respectively, a processing circuit 266 for processing the resultinganalog and digital signals, a memory circuit 268 which may includevolatile (e.g., RAM) and non-volatile (e.g., ROM, EEROM, EEPROM) memoryfor storing code (e.g., boot or operating code) and data (e.g.,calibration/configuration data; variables). An interface circuit 270 isprovided for communication via data bus 72, and a lamp driver circuit272 is provided for driving status lamps (e.g., cylinder status).

Analog signal conditioning and multiplexer circuits 262 and 264 bothinclude hardware filtering circuits for filtering the signals fromcommand devices 38. Analog circuit 262 also includes analog switchcircuits (e.g., HC4051N analog switches) for multiplexing the filteredsignals. Digital circuit 264 also includes digital switches (e.g.,74HC299 8-bit shift/storage registers) to multiplex the filteredsignals. Select signals for the multiplexers are provided by processingcircuit 266.

Processing and memory circuits 266 and 268 include a processor (e.g., an80C198 microcontroller from Intel) for reading the multiplexed signals.Analog signals are digitized using an analog-to-digital converter in themicrocontroller. A combination interface circuit (e.g., a PSD312 fromWafer Scale Integration) provides RAM, ROM for boot and operating code,and logic for generating the select signals. FLASH memory (e.g., a29C010 circuit) is also included.

Interface circuit 270 includes bus controller (e.g., an 82527) and CANtransceiver (e.g., 82C250) circuits for transmitting and receiving datafrom bus 72. Lamp driver 272 includes an LTC1485N circuit for drivingsystem status lamps (e.g., slip; end-of-row; cylinder status).

Referring to FIG. 5, processing circuit 266 is programmed to perform theprocesses shown. In process 300, processing circuit 266 samples thedigitized analog voltages from command devices 38 at a predeterminedsample period (e.g., 10 msec). The digitized voltages are filtered andthe filtered values are stored as filtered analog readings 302. Inprocess 304, processing circuit 266 range checks filtered analogreadings 302 and latches an error flag 306 for any signal which is outof range for a given amount of time (e.g., 250 msec).

In process 308, processing circuit 266 samples the status of the inputsfrom each switch command device 38 at a predetermined sample period(e.g., 10 msec). The status of the inputs from each switch areconsidered unchanged for a debounce time (e.g., 50 msec) after a changein status of any input from that switch. The status of the switches arestored as switch states 310.

Processing circuit 266 also checks the inputs from particular switchesfor conflicting signals. If inputs from a switch conflict for less thanan error debounce time, the status of the inputs is considered to be thelast valid status. However, if inputs from a particular switch conflictfor more than the error debounce time, an error flag 306 is latched forthe switch. For example, a conflict exists if the extend and the retractinputs from valve control switch 48 are both active. If the conflictexists for less than 250 msec, the status of the inputs is considered tobe the last valid status. However, if the conflict remains for more than250 msec, an error flag 306 is latched for valve control switch 48. Foranother example, a conflict exists if the extend and retract limitinputs from switch 70 are both active, and error flag 306 for switch 70is latched after 250 msec.

In process 312, processing circuit 266 receives incoming messages frombus 72 such as lamp command data used to control the lamps in process314. The incoming messages also include configuration data during normaloperation and calibration/configuration control signals from aninstrumentation control unit (ICU). In process 316, processing circuit266 generates calibration and configuration data using filtered analogreadings 302 and switch states 310 in response to the ICU controlsignals.

In process 318, processing circuit 266 generates outgoing messages fordata bus 72 using filtered analog readings 302, switch states 310, errorflags 306 and configuration/calibration data from processes 312 and 316.The outgoing messages include the debounced status of each switch, theswitch error flags, and configuration data indicating whether anyswitches are not available (i.e., the system is not configured for theseswitches).

Processing circuit 266 also scales the filtered analog readings 302 andtransmits the scaled values in the outgoing data bus messages. Thescaling provides accurate command signals even if relatively lowaccuracy potentiometers are used. The scaling of the filtered analogreadings 302 for auxiliary valve control levers 40-46 is shown in FIG.6.

The top plot shows the mechanical angle of control levers 40-46 at theextend, retract and float detent positions relative to the neutralposition. Vertical bars surrounding each of these positions represents adeadband wherein the command value does not change.

The horizontal axis of the bottom graph shows the filtered analogreading and includes points representing minimum and maximum voltagesexpected to be read (MIN and MAX), minimum, ideal and maximum voltagesexpected when control levers 40-46 are in the extend detent duringcalibration (MIN₋₋ CAL₋₋ EXTEND, CAL₋₋ EXTEND, MAX₋₋ CAL₋₋ EXTEND),voltages required to enter and exit the extend detent (ENTER₋₋ EXTENDand EXIT₋₋ EXTEND), voltage at which full flow in the extend directionbegins (FULL₋₋ FLOW₋₋ EXTEND), minimum, ideal and maximum voltagesexpected when control levers 40-46 are in the neutral position (MIN₋₋NEUTRAL, NEUTRAL, MAX₋₋ NEUTRAL), voltage at which full flow in theretract direction beings (FULL₋₋ FLOW₋₋ RETRACT), voltages required toexit and enter the retract detent (EXIT₋₋ RETRACT and ENTER₋₋ RETRACT),minimum, ideal and maximum voltages expected to be read when controllevers 40-46 are in the retract detent during calibration (MIN₋₋ CAL₋₋RETRACT, CAL₋₋ RETRACT, MAX₋₋ CAL₋₋ RETRACT), and voltages required toexit and enter the float detent (EXIT₋₋ FLOAT and ENTER₋₋ FLOAT). Theideal center of the neutral position (NEUTRAL) is the average of CAL₋₋EXTEND and CAL₋₋ RETRACT. The differences between ENTER₋₋ EXTEND andEXIT₋₋ EXTEND, EXIT₋₋ RETRACT and ENTER₋₋ RETRACT, and EXIT₋₋ FLOAT andENTER₋₋ FLOAT, represents hysteresis.

The vertical axis of the bottom graph shows the command signalsbroadcast on bus 72. The command signals include a value of 0 (extend),1 (full flow extend), 125 (neutral), 248 (full flow retract), 249(retract), 250 (float) and 254 (error). The command values for readingsbetween FULL₋₋ FLOW₋₋ EXTEND and MIN₋₋ NEUTRAL, and MAX₋₋ NEUTRAL andFULL₋₋ FLOW₋₋ RETRACT, are proportional to the full flow values and aredetermined using straight-line equations. Thus, unique command signalvalues are associated with the neutral position and with each detentposition, and proportional command values are associated with controllever positions between the extend detent and neutral positions, andbetween the neutral and retract detent positions. Proportional commandvalues may be used for precision operations or for creeping.

FIG. 7 shows the scaling of the filtered analog readings 302 for flowlimit control knobs 58-66. The horizontal axis shows the filtered analogreading and includes points representing the minimum and maximum valuesexpected to be read when the potentiometer is turned fullycounter-clockwise (MIN₋₋ LOW₋₋ SIDE and MAX₋₋ LOW₋₋ SIDE) and fullyclockwise (MIN₋₋ HIGH₋₋ SIDE and MAX₋₋ HIGH₋₋ SIDE). The vertical axisshows the command values broadcast on bus 72 including a value of 0 (0%flow limit), 250 (100% flow limit), and 254 (error). The command valuesfor readings between MAX₋₋ LOW₋₋ SIDE and MIN₋₋ HIGH₋₋ SIDE areproportional and are given by straight-line equations. The scaling forother inputs is similar.

Alternatively, the scaled command signals could represent the positionof the respective valve control lever 40-46 scaled by the respectiveflow limit. For example, if the input from flow limit control knob 58corresponds to a flow limit of X and control lever 40 is in the extenddetent position, the scaled command signal for valve 1 could representan extend flow rate of X. The combination of the control lever positionand flow limit for valve 1 into a single command signal could be used todecrease the loading on bus 72.

Referring to FIG. 8, auxiliary control unit 26 includes an interfacecircuit 330 for transmitting and receiving messages via bus 72, aprocessing circuit 332 for generating stepper motor control data 334-342in response to the command signals from armrest control unit 24, steppermotor controllers 344-352 for generating control signals 354-362 for thestepper motors, and H-bridge driver circuits 364-372 for generatingvalve control signals 74-82 for valve assemblies 28-36. A memory circuit374 may include volatile (e.g., RAM) and non-volatile (e.g., ROM, EEROM)memory. Processing circuit 332 also receives optional feedback signal112 and a power signal from key switch 108.

Interface circuit 330 includes bus controller (e.g., an 82527) and CANtransceiver (e.g., 82C250) circuits for communication via bus 72.Processing and memory circuits 332 and 374 include a processor circuit(e.g., a 80C198 microcontroller) and a combination interface circuit(e.g., PSD312). Each stepper motor controller 344-352 includes an L297circuit, and each H-bridge driver circuit 364-372 includes two L6203drivers (one L6203 driver for each stepper motor phase). Auxiliarycontrol unit 26 generates valve control signals 74-82 for moving therespective valve to the desired valve position.

Referring to FIGS. 9A-9C, processing circuit 332 is programmed tocontrol auxiliary valve assemblies 28-36 in one of several valve states.The desired valve state is determined during background processing.After the desired valve state is determined, control signals 74-82 areupdated and strobed to valve assemblies 28-36 during foregroundprocessing triggered on a time basis. Valve assemblies 28-34 arecontrolled in the following states:

FLOATING: Lever 40-46 is at float detent position;

FULL RETRACT: Lever is at full retract position;

PROP. RETRACT: Lever is at proportional retract position;

NEUTRAL: Lever is at neutral position;

IDLE: Transition state (wait for lever to pass through neutral beforestate can change);

PROP. EXTEND: Lever is at proportional extend position;

FULL EXTEND: Lever is at full extend position;

DEAD: Remove power from valve and disable valve.

Valve assembly 36, controlled by switch 48 instead of a lever, iscontrolled in the following states:

FULL RETRACT: Switch 48 is at retract position;

NEUTRAL: Switch is at neutral position;

IDLE: Transition state (wait for switch to pass through neutral beforestate can change);

FULL EXTEND: Switch is at extend position;

DEAD: Remove power from valve and disable valve.

Referring to process 400 illustrated in FIG. 9A, processing circuit 332performs initialization logic upon power up. Power-up functions includesetting error codes 402 (e.g., EEPROM data invalid; bus error; regulatedvoltage range error; valve present when not supposed to be; valve notpresent when supposed to be; valve phase circuit error), setting valvestates 404 to DEAD when errors are detected and IDLE when the valves arefunctional, determining if cylinder position feedback signal 112 ispresent (i.e., within range) and clearing extend and retract setpoints406 if signal 112 is not present (indicating that remote cylinderposition mode may not be used for valve 1), setting cylinder lightstatus to "ON" when signal 112 is present and setpoints 406 are set andto "OFF" otherwise, and entering a control loop when the power-up logicis complete. Status data is transmitted via data bus 72.

In process 408, processing circuit 332 handles background auxiliaryfunctions (described in relation to FIG. 9B) to update valve states 404,extend and retract set points 406, valve flow rates 410 and valve targetpositions 412 in response to incoming messages from bus 72 which containthe command signals from armrest control unit 24. In foreground process414, processing circuit 332 generates stepper motor control signals334-342 in response to flow rates 410 and target positions 412.

Referring to FIG. 9B, the operation of processing circuit 332 in process408 is shown in further detail. In process 430, processing circuit 332adjusts the flow limits for each valve, updates the automatic kick-outtimers for each valve, adjusts the automatic kick-out time delay foreach valve, and sets the extend or retract positions as explainedfurther in relation to FIG. 9C.

In process 432, processing circuit 332 updates valve states 404, flowrates 410 and valve target positions 412 as follows. State 404 for valve5 is set to DEAD and the valve is disabled when valve control switch 48indicates both extend and retract commands. Then, for each valve whichis not in DEAD state, valve state 404 is updated according to the eventstate table of FIG. 10. The horizontal axis represents the current valvestate, the vertical axis represents a detected event, and the tableoutput represents the updated valve state. For example, if the state ofvalve 3 is FULL RETRACTING, and control lever 44 is moved to aproportional retracting position (i.e., a retract feel position), thevalve state becomes the PROPORTIONAL RETRACTING state. Then, the valvestate is set to DEAD for each valve with a range-failed control leverposition. Valve target positions 412 are updated based upon the updatedvalve state.

Then, for each valve for which the respective control lever 40-46 wasjust moved to the extend detent or retract detent position (or for valve5 if switch 48 was just moved to the extend or retract switch position),an automatic kick-out timer (set using kick-out timer set knob 68) isactivated and the flow rate for the valve is set to the valve's flowlimit. However, the automatic kick-out timer is deactivated for eachvalve for which the respective valve control lever was just moved out ofthe extend detent or retract detent position. Then, for valves 1-4 only,if the control lever is in a feel (i.e., proportional) position, theautomatic kick-out timer is deactivated and the flow rate is set to aproportion of the valve's flow limit determined by the control leverposition for that valve. Finally, the flow rate is set to neutral orzero flow for each valve in the NEUTRAL, IDLE or DEAD state. Thus, theflow rate for each valve is set to a value which depends upon a flowlimit setting selected by the operator for the particular attachment.

Referring to FIG. 9C, in process 434, processing circuit 332 adjusts theflow limit for each valve to correspond to a flow control setting fromthe respective flow limit control knob 58-66, and sets an error code ifthe flow control setting is out of range. In process 436, processingcircuit 332 adjusts the automatic kick-out timer for each valve when thevalve state is not DEAD and the timer is enabled and running. Note thatkick-out timer disable switches 50-56 disable the timers when therespective guide 208 is in the MOTOR rotational position.

In process 438, processing circuit 334 adjusts the automatic kick-outtime delay for each valve which is not DEAD as follows. In response tokick-out timer enable signals derived from switches 50-56 and receivedfrom bus 72, automatic kick-out timers are enabled and the timers arestarted when the valve state corresponds to an extend detent or retractdetent event. The kick-out timers are disabled in response to kick-outtimer disable signals from bus 72. Then, if the automatic kick-out delaytime base set by knob 68 has changed, the new value is range-checked(e.g., the valid range may be 1-15). If the new time base is out ofrange, an error code is set and a default time base is used. Theautomatic kick-out delay for each valve is updated to the new time base.

In process 440, processing circuit 332 sets the extend and retract setpoints 406 as follows. If the extend and retract set point requests fromswitch 70 are both active, an error code is set. Otherwise, the extendset point is set equal to position feedback signal 112 in response to anextend set point request, and the retract set point is set equal toposition feedback signal 112 in response to a retract set point request.Once both set points are set, the cylinder status light is set "ON".

In operation, an operator independently controls the flow of hydraulicfluid through auxiliary valves 1-4 in one of several modes selectedusing arm 224 to rotate guide 208. Then, the respective control lever40-46 is moved to a flow command position within an allowed range. Forvalve 5, the flow rate is controlled using switch 48. Maximum flow ratethrough each valve is set independently using flow limit control knobs58-66. Using detent and feel lever positions, flow rates are commandedfor valves 1-4 which correspond to a maximum extend flow rate, aproportional extend flow rate, a neutral flow rate, a proportionalretract flow rate and a maximum retract flow rate. An operator can alsoselect a float valve position wherein the valve spool is positioned suchthat there is no forced flow in either direction. In float position, theattachment may, for example, move up or down with the ground, or movedown by the force of gravity. For valve 5, the operator can command amaximum extend flow rate, a neutral flow rate, and a maximum retractflow rate.

Typically, the maximum extend and maximum retract flow rates continuefor a predetermined time period after the respective control lever ismoved into the extend detent or raise detent position (or extend orretract switch position). After this time period, an automatic kick-outoccurs and the flow drops to neutral (i.e., 0 flow). The automatickick-out prevents the system from remaining in "high standby" status androbbing the system of power when, for example, a hydraulic cylinder hasalready reached a desired position Typically, the kick-out time periodwill be set using knob 68 to supply flow for a time period (e.g., 10sec) longer than the time required to move the slowest attachment (e.g.,8 sec).

If the control lever moves out of the extend detent or retract detentposition before a kick-out occurs, the timer is reset and flow ratefollows the control lever proportionately. If the control lever is notmoved until after a kick-out occurs, the control lever must be firstmoved to the neutral position before the flow rate can be controlledagain. In addition, if guide 208 of control lever assembly 160 is movedinto the "MOTOR" position, the automatic kick-out function is disabledand the flow continues indefinitely. MOTOR position, then, is used forhydraulic motors which require continuous flow.

Valve 1 can also operate in an optional cylinder position mode wherein,when control lever 40 is moved into the extend detent or retract detentposition, flow continues until a cylinder position feedback signalreaches a predetermined extend or retract position. The predeterminedextend and retract positions are set by the operator using limit switch70, and the cylinder position mode is used when a feedback signal ispresent and the extend and retract limits have been stored in memory.

In describing the scaling performed by processing circuit 266 of armrestcontrol unit 24 in relation to FIG. 6, it was assumed that the positionsof control levers 40-46 can be accurately determined by comparing thefiltered analog readings to expected values. The relatively low accuracyof typical control lever sensing circuits, however, makes suchdeterminations difficult. For example, potentiometer 238 may have anaccuracy of +/-10%. The problem is particularly troublesome where, ashere, a control lever is positionable in one or more detent positionswhich must be accurately distinguished by a control circuit. The detentpositions cause, for example, the breakpoints in the line shown in FIG.6. Thus, a relatively accurate method of reading the operating positionsof control lever 40-46 is required.

Therefore, auxiliary hydraulic system 12 calibrates control levers 40-46and generates calibrated command signals. The calibration involvesmoving each control lever 40-46 into the extend detent and retractdetent positions, converting the resulting position signals sensed bypotentiometer 238 into extend and retract calibration values, andstoring the calibration values in EEPROM as in the memory map shown inFIG. 11. CAL₋₋ AUXn₋₋ EXTEND and CAL₋₋ AUXn₋₋ RETRACT correspond to thedigitized readings when the nth control lever (n=1 to 4) is moved intothe extend detent and retract detent positions, respectively, during acalibration procedure.

During operation, when control levers 40-46 are in operating positions,processing circuit 266 uses stored calibration values CAL₋₋ AUXn₋₋EXTEND and CAL₋₋ AUXn₋₋ RETRACT for CAL₋₋ EXTEND and CAL₋₋ RETRACT inFIG. 6, respectively. Some or all of the other filtered A/D readingvalues in FIG. 6 may be based upon these calibration values. Forexample, in a preferred embodiment using a 10-bit A/D converter, thevalues are defined as follows:

    ______________________________________    NAME OF POINT   ANGLE    A/D READING    ______________________________________    MIN                      60    MIN.sub.-- CAL.sub.-- EXTEND                             74    CAL.sub.-- EXTEND                    -18°                             CAL.sub.-- EXTEND    MAX.sub.-- CAL.sub.-- EXTEND                             194    ENTER.sub.-- EXTEND      CAL.sub.-- EXTEND + 30    EXIT.sub.-- EXTEND       CAL.sub.-- EXTEND + 90    FULL.sub.-- FLOW.sub.-- EXTEND                             CAL.sub.-- EXTEND + 120    MIN.sub.-- NEUTRAL       NEUTRAL - 60    NEUTRAL          0°                             (CAL.sub.-- EXTEND +                             CAL.sub.-- RETRACT)/2    MAX.sub.-- NEUTRAL       NEUTRAL + 60    FULL.sub.-- FLOW.sub.-- RETRACT                             CAL.sub.-- RETRACT - 120    EXIT.sub.-- RETRACT      CAL.sub.-- RETRACT - 90    ENTER.sub.-- RETRACT     CAL.sub.-- RETRACT - 30    MIN.sub.-- CAL.sub.-- RETRACT                             599    CAL.sub.-- RETRACT                    +18°                             CAL.sub.-- RETRACT    MAX.sub.-- CAL.sub.-- RETRACT                             719    EXIT.sub.-- FLOAT        CAL.sub.-- RETRACT + 60    ENTER.sub.-- FLOAT       CAL.sub.-- RETRACT + 90    MAX                      932    ______________________________________

Thus, the scaled position signals are calibrated using the calibrationvalues.

Referring to FIG. 12, calibration of auxiliary hydraulic system 12 andof other systems connected to bus 72 is controlled by an instrumentationcontrol unit (ICU) 500. ICU 500 includes an ICU control circuit 502, aninterface circuit 504 for communication via bus 72, input devices 506including PROGRAM, INCREMENT and DECREMENT buttons for operatorcalibration inputs, a reconfigurable display unit 508 for providingfeedback to the operator, and a memory circuit 510.

Referring to FIG. 13, the calibration procedure for auxiliary hydraulicsystem 12 is shown. Auxiliary hydraulic system 12, and other systems,are calibrated and configured through ICU 500. The calibration optionsare presented to the operator via display unit 508, and the options areselected by pressing the PROGRAM ("PROG") and INCREMENT/DECREMENTbuttons (arrows). For example, the operator can cycle throughcalibration options for the hitch, throttle and auxiliary hydraulicsystem 12.

Using the INCREMENT/DECREMENT buttons, the operator is presented withdisplay 520. "CALIB" on the top line of display 520 indicates thatcontrol levers 40-46 will be calibrated if the "PROG" button isactuated. After pressing "PROG", display 522 shows "AUX₋₋ EXT" torequest the operator to activate valve control switch 48 to the EXTENDposition and to move each control lever 40-46 to the extend detentposition. The top line of display 522 indicates the command deviceswhich have been moved to the extend position (control levers 40, 42 and46; switch 48). The "-" indicates that control lever 44 is not in thegeneral area expected for the extend detent position.

Another press of the "PROG" button presents the operator with display524. "AUX₋₋ RET" requests the operator to activate valve control switch48 to the RETRACT position and to move each control lever 40-46 to theretract detent position. The top line of display 524 indicates thecommand devices which have been moved to the retract position (controllevers 40 and 46; switch 48). "-" indicates that control lever 42 is notin the general area expected for the retract detent position. "X"indicates that a valid extend position was not noted for control lever44 in the previous step. Calibration of auxiliary hydraulic system 12 isnow complete, and the operator can exit by pressing "PROG" again.

Auxiliary hydraulic system 12 can be configured to use different numbersof auxiliary hydraulic valves. The configuration of valves 1-4 is basedupon whether valid calibration values are stored in EEPROM. The valve isassumed to be present if valid calibration values are stored, and isotherwise assumed to be not present. The configuration of valve 5 isbased upon whether control switch 48 was active during calibration basedupon a flag (AUX5₋₋ PRESENT in FIG. 11) stored in EEPROM.

While the embodiments illustrated in the FIGURES and described above arepresently preferred, it should be understood that these embodiments areoffered by way of example only. The invention is not intended to belimited to any particular embodiment, but is intended to extend tovarious modifications that nevertheless fall within the scope of theappended claims.

What is claimed is:
 1. An operator control console for a working vehicleequipped with an auxiliary hydraulic system, the auxiliary hydraulicsystem including a fluid pump, a plurality of fittings, an auxiliaryvalve assembly for controlling the flow of fluid between the fluid pumpand the fittings in response to control signals, and an auxiliarycontrol circuit for receiving command signals and generating the controlsignals therefrom, comprising:a console cover; at least one controllever extending above the console cover and moveable between a pluralityof positions including neutral and maximum flow positions; a sensingcircuit for generating a signal representative of the position of thecontrol lever; at least one flow limit input device including a handleextending above the console cover and configured to generate a signalrepresentative of a flow limit; and a console control circuit coupled tothe sensing circuit and the flow limit input device, wherein the consolecontrol circuit is configured to generate the command signals, thecommand signals corresponding to a flow rate between a neutral flow rateand the flow limit depending upon the position of the control lever. 2.The operator control console of claim 1 wherein the command signalsinclude control lever command signals and flow limit command signalsrepresenting the positions of the control lever and the flow limit,respectively.
 3. The operator control console of claim 1 wherein thecommand signals are representative of the position of the control leverafter being scaled by the flow limit.
 4. The operator control console ofclaim 1 wherein the command signals correspond to a proportional flowrate between the neutral flow rate and the flow limit when the controllever is between the neutral and the maximum flow positions.
 5. Theoperator control console of claim 4 wherein the maximum flow position isa detent position, and the command signals correspond to the neutralflow rate and the flow limit when the control lever is moved to theneutral and maximum flow detent positions, respectively.
 6. The operatorcontrol console of claim 1 wherein the control lever has extend detent,neutral and retract detent positions, and the command signals correspondto maximum extend, neutral and maximum retract flow rates when thecontrol lever is moved to the extend detent, neutral and retract detentpositions, respectively, the maximum extend and retract flow rateshaving magnitudes equal to the flow limit.
 7. The operator controlconsole of claim 6 wherein the command signals correspond toproportional flow rates when the control lever is between the extenddetent and the neutral positions, and when the control lever is betweenthe neutral and the retract detent positions.
 8. The operator controlconsole of claim 6 wherein the control lever further has a float detentposition, and the command signals correspond to float command signalswhen the control lever is moved to the float detent position.
 9. Theoperator control console of claim 1 further comprising a lever lockassembly coupled to the control lever and configured to limit themovement of the control lever between one of a plurality ofpredetermined ranges.
 10. The operator control console of claim 9wherein the control lever has extend detent, neutral, retract detent andfloat detent positions and, when a first range of movement is selected,the lever lock assembly retains the control lever against movement inthe neutral position and the command signals correspond to the neutralflow rate.
 11. The operator control console of claim 10 wherein, when asecond range of movement is selected, the control lever is moveablebetween the extend detent, neutral and retract detent positions but isprevented from entering the float detent position.
 12. The operatorcontrol console of claim 10 wherein, when a second range of movement isselected, the control lever is moveable between the extend detent,neutral, retract detent and float detent positions.
 13. The operatorcontrol console of claim 10 wherein, when a second range of movement isselected, the control lever is moveable between the neutral, retractdetent and float detent positions but is prevented from entering theextend detent position.
 14. The operator control console of claim 10wherein, when a second range of movement is selected, the control leveris moveable between the retract detent and float detent positions but isprevented from entering the neutral and extend detent positions.
 15. Theoperator control console of claim 1 wherein the command signalscorrespond to the flow limit for only a predetermined time period afterthe control lever is moved to the maximum flow position.
 16. Theoperator control console of claim 15 further comprising a timer setinput device coupled to the console control circuit and configured togenerate a signal representative of the predetermined time period. 17.The operator control console of claim 16 having at least two controllevers, wherein the timer set input device determines the samepredetermined time period for each control lever.
 18. The operatorcontrol console of claim 1 further comprising an operator-actuatedswitch having first and second states, wherein the command signalscorrespond to the flow limit for only a predetermined time period afterthe control lever is moved to the maximum flow position when the switchis in the first state, and the command signals correspond to the flowlimit continuously after the control lever is moved to the maximum flowposition when the switch is in the second state.
 19. The operatorcontrol console of claim 15 wherein the command signals correspond to aproportional flow rate if the control lever is moved from the maximumflow position to a position between the maximum flow and neutralpositions before completion of the predetermined time period.
 20. Theoperator control console of claim 1 further comprising an interfacecircuit coupled to the console control circuit and configured to formatthe command signals for transmission on a communication bus.
 21. Theoperator control console of claim 1 further including a feedbackinterface for receiving feedback signals, wherein the command signalsare based upon the position of the control lever and the flow limituntil the feedback signals represent a predetermined value.
 22. Theoperator control console of claim 1 wherein the console cover includes afirst surface portion for mounting the control lever and a secondsurface portion for mounting the flow limit input device, and the secondsurface portion is covered by a moveable cover.
 23. An auxiliaryhydraulic system for a working vehicle having an operator station,comprising:a hydraulic pump supported by the vehicle for providinghydraulic fluid under pressure; a plurality of auxiliary hydraulicfittings configured to be connected to auxiliary attachments; aplurality of electrically-actuated auxiliary valve assemblies configuredto control the supply of hydraulic fluid from the pump to the auxiliaryhydraulic fittings in response to control signals; an operator controlconsole mounted at the operator station, the control consolecomprising:a console cover; a plurality of control levers extendingabove the console cover and moveable between a plurality of positionsincluding neutral and maximum flow positions; a plurality of sensingcircuits, each sensing circuit coupled to one of the control levers forgenerating a signal representative of the position of the respectivecontrol lever; a plurality of flow limit input devices, each flow limitinput device including a handle extending above the console cover andconfigured to generate a signal representative of a flow limit for oneof the valve assemblies; and a console control circuit coupled to thesensing circuits and the flow limit input devices, wherein the consolecontrol circuit is configured to generate command signals for each valveassembly which correspond to a flow rate between a neutral flow rate andthe flow limit for the respective valve assembly depending upon theposition of the respective control lever; and an auxiliary controlcircuit coupled to the auxiliary valve assemblies and the operatorcontrol console, the auxiliary control circuit configured to receive thecommand signals and to generate the control signals therefrom, and toapply the control signals to the valve assemblies, whereby the supply ofhydraulic fluid to the auxiliary valve fittings depends upon thepositions of the control levers and the flow limits.
 24. The auxiliaryhydraulic system of claim 23 further comprising a communication bus forcommunicating the command signals from the console control circuit tothe auxiliary control circuit.
 25. The auxiliary hydraulic system ofclaim 24 wherein the auxiliary control circuit comprises:an interfacecircuit coupled to the communication bus and configured to receive thecommand signals from the console control circuit; a processing circuitcoupled to the interface circuit and configured to generate steppermotor control data for each of the auxiliary valve assemblies; and aplurality of stepper motor controller circuits coupled to the processingcircuit, each stepper motor controller circuit configured to generatestepper motor control signals for one of the auxiliary valve assembliesbased upon the stepper motor control data.
 26. The auxiliary hydraulicsystem of claim 25 wherein the auxiliary control circuit furtherincludes a plurality of H-bridge driver circuits for receiving thestepper motor control signals and for driving stepper motors associatedwith each auxiliary valve assembly.
 27. The auxiliary hydraulic systemof claim 23 wherein the auxiliary control circuit further includes afeedback interface for receiving feedback signals from one of theauxiliary attachments, and the control signal applied to the auxiliaryvalve assembly associated with the one auxiliary attachment is set to aneutral value when the feedback signals reach a predetermined value. 28.An operator control console for a working vehicle equipped with acommunication bus, comprising:a console cover; a first input deviceextending above the console cover and moveable between a plurality ofpositions including a first predefined position; a sensing circuitcoupled to the first input device and configured to generate a signalrepresentative of the position of the first input device; a second inputdevice extending above the console cover and configured to generate asignal representative of a parameter limit; a control circuit coupled tothe sensing circuit and the second input device, wherein the controlcircuit is configured to generate command signals which correspond tothe parameter limit when the first input device is moved to the firstpredefined position; and an interface circuit coupled to the controlcircuit, wherein the interface circuit formats the command signals fortransmission on the communication bus.
 29. The operator control consoleof claim 28 wherein the plurality of positions further includes a secondpredefined position and proportional positions between the first andsecond predefined positions, and the command signals are proportional tothe parameter limit when the first input device is moved between thefirst and second predefined positions.